If you are willing to trade a few globals to obtain speed, then a dispatch table might allow for reasonable maintanence:

my( $hrs, $mins, $secs, $day, $month, $year, ... );

my %res = (
    qr[(\d\d):(\d\d):(\d\d)]           => sub{($hrs,$mins,$secs) = ($1
+,$2,$3) },
    qr[(\d\d)/(\d\d)/(\d\d(?:\d\d)*)] => sub{($day,$month,$year) = ($1
+,$2,$3) },
    ...,
    '' => sub{ die "Unknown date format" },
};

...

$maybeTime =~ $_ and $res{ $_ }->() for keys %res;
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